1. Field of the Invention
The present invention generally relates to color image forming devices such as photocopiers and printers that use xerography. More specifically, the present invention relates to image forming devices that transfer toner images formed on an image carrier onto a recording medium via an intermediate transfer member.
2. Background Information
In photocopiers and printers and the like that use xerography, an image forming method in which toner images formed on a photosensitive drum as an image carrier are transferred not to the recording medium but temporarily to an intermediate transfer member, and then the toner images on the intermediate transfer member are transferred to the recording medium is known. By using this method, it is possible to reduce transfer defects and color registration errors due to many causes such as the holding or surface condition of the recording medium.
However, when transferring the toner images formed on the intermediate transfer member onto the recording medium, a part of the toner is not transferred to the recording medium, but remains on the intermediate transfer member. This residual transfer toner remaining on the intermediate transfer member can have a deleterious effect on the next image forming operation. Therefore, image forming devices that use an intermediate transfer member are provided with a cleaning device to clean the residual transfer toner remaining on the intermediate transfer member after transfer from the intermediate transfer member to the recording medium.
The intermediate transfer member cleaning device has a simple configuration and can be installed at low cost, so blade cleaning systems in which a blade made from urethane rubber or the like is pressed against the intermediate transfer member to scrape the residual transfer toner off the intermediate transfer member are used. However, in the blade cleaning method the blade is pressed against the intermediate transfer member with a reasonable force, which causes the load torque to increase and can cause image defects such as jitter and so on. Also, if the blade is provided near the secondary transfer area, this can cause contamination of the sheet transport path with particles of toner and so on, which can cause image defects.
Therefore, image forming devices that use a fur brush cleaning method have been proposed to prevent load torque on the intermediate transfer member and image defects due to suspension of particles of toner (for example, see Japanese Patent Application Laid-open No. 2003-270972). In image forming devices that use the fur brush method, a fur brush in which brush fibers are applied to the surface of a cylindrical base member is rotated while in contact with the intermediate transfer member, and by applying a cleaning bias to the fur brush the toner is recovered both mechanically and electrically.
However, in image forming devices that use the fur brush method, it is necessary to provide an opposing electrode in a position in opposition to the fur brush that sandwiches the intermediate transfer belt to recover the toner electrically. Therefore, the configuration of the image forming device becomes more complex, which can increase the cost, and so on. Also, if the fur brush is provided near the area where the transfer from the intermediate transfer belt to the sheets occurs, the cleaning bias applied to the fur brush can change the transfer bias so that stable image output can be difficult.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved image forming device. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.